electron transfer sites will be in focus. The extraction of these parameters is shown
on the example of wastewater derived mixed culture biofilms that are dominated by
Geobacter species (Logan and Rabaey 2012). These wastewater derived biofilms are
gained by a simple electrochemical selection procedure as confirmed by copious
research groups around the world (Rabaey and Rozendal 2010). The BES
connecting microorganisms be a symbol of a major domain of research with
applications in waste treatment for energy and chemical generation (Lagarde and
Jaffrezic-Renault 2011) or biosensors (Reguera et al. 2005; Sevda et al. 2020). A key
challenge to these ends is to make certain the electrochemical communication
between viable bacteria and electrodes. For instance, electron transfer has been
reported for both monolayer bacteria and conductive biofilms deposited onto electrode surfaces. The biofilm conductivity is attributed either to electrically conductive
pili or electron hopping between membrane bound cytochromes or small redox
compounds that diffuse between the bacteria and the electrode surface (Reguera
et al. 2005). Although natural biofilms offer more than a few advantages in
bioelectrochemical applications, “artificial” designs in which the microorganisms
are powerless within appropriate matrices are of current interest in order to improve
the electron transfer reactions. Moreover, such “artificial” environment could provide a unique opportunity to better control the microorganism strain and environment, with strong interest for both fundamental consideration and applied devices,
e.g. whole cell biosensors.
Microbial fuel cells (MFCs) are systems that can convert the chemical energy in
organic compounds into electricity using the catalytic action of an anaerobic microorganism. These microorganisms are called exoelectrogens (Dominguez-Benetton
2012) and they produce electrical energy oxidizing organic matter. MFCs generally
consist of two parts: an anode and a cathode. Organic compounds are degraded by
exoelectrogens on the anode surfaces, and CO 2 , electrons, and protons are produced
as end products. The generated electrons are delivered to the cathode by bacteria
following an external circuit, and protons are also moved through the external circuit
for electro-neutrality (Schröder 2007). At the aerobic cathode, water is produced by a
reaction among protons, electrons, and oxygen (electron acceptor), and electricity is
generated. The microbial fuel cell consists of two compartments, the anodic and
cathodic chambers that are separated by a selectively permeable, cation-specific
membrane (Fig. 5.1).
The anodic chamber consists of microbes suspended under anaerobic conditions
in the analyte and the cathodic chamber contains the electron acceptor. In essence,
the electron donor is physically separated from the terminal electron acceptor across
the two chambers (Sevda et al. 2018).
Many studies have been conducted on wastewater treatment using MFCs because
they can generate electricity and treat wastewater simultaneously (Logan and
Rabaey 2012). There are five advantages of MFCs for wastewater treatment.
(1) MFCs can convert chemical energy of substrates into electricity directly. (2) A
smaller amount of activated sludge is produced from MFCs than from other methods
during wastewater treatment. (3) This method is environmentally friendly and
5 Microbiology of Bioelectrochemical System
107
on the example of wastewater derived mixed culture biofilms that are dominated by
Geobacter species (Logan and Rabaey 2012). These wastewater derived biofilms are
gained by a simple electrochemical selection procedure as confirmed by copious
research groups around the world (Rabaey and Rozendal 2010). The BES
connecting microorganisms be a symbol of a major domain of research with
applications in waste treatment for energy and chemical generation (Lagarde and
Jaffrezic-Renault 2011) or biosensors (Reguera et al. 2005; Sevda et al. 2020). A key
challenge to these ends is to make certain the electrochemical communication
between viable bacteria and electrodes. For instance, electron transfer has been
reported for both monolayer bacteria and conductive biofilms deposited onto electrode surfaces. The biofilm conductivity is attributed either to electrically conductive
pili or electron hopping between membrane bound cytochromes or small redox
compounds that diffuse between the bacteria and the electrode surface (Reguera
et al. 2005). Although natural biofilms offer more than a few advantages in
bioelectrochemical applications, “artificial” designs in which the microorganisms
are powerless within appropriate matrices are of current interest in order to improve
the electron transfer reactions. Moreover, such “artificial” environment could provide a unique opportunity to better control the microorganism strain and environment, with strong interest for both fundamental consideration and applied devices,
e.g. whole cell biosensors.
Microbial fuel cells (MFCs) are systems that can convert the chemical energy in
organic compounds into electricity using the catalytic action of an anaerobic microorganism. These microorganisms are called exoelectrogens (Dominguez-Benetton
2012) and they produce electrical energy oxidizing organic matter. MFCs generally
consist of two parts: an anode and a cathode. Organic compounds are degraded by
exoelectrogens on the anode surfaces, and CO 2 , electrons, and protons are produced
as end products. The generated electrons are delivered to the cathode by bacteria
following an external circuit, and protons are also moved through the external circuit
for electro-neutrality (Schröder 2007). At the aerobic cathode, water is produced by a
reaction among protons, electrons, and oxygen (electron acceptor), and electricity is
generated. The microbial fuel cell consists of two compartments, the anodic and
cathodic chambers that are separated by a selectively permeable, cation-specific
membrane (Fig. 5.1).
The anodic chamber consists of microbes suspended under anaerobic conditions
in the analyte and the cathodic chamber contains the electron acceptor. In essence,
the electron donor is physically separated from the terminal electron acceptor across
the two chambers (Sevda et al. 2018).
Many studies have been conducted on wastewater treatment using MFCs because
they can generate electricity and treat wastewater simultaneously (Logan and
Rabaey 2012). There are five advantages of MFCs for wastewater treatment.
(1) MFCs can convert chemical energy of substrates into electricity directly. (2) A
smaller amount of activated sludge is produced from MFCs than from other methods
during wastewater treatment. (3) This method is environmentally friendly and
5 Microbiology of Bioelectrochemical System
107